The invention relates to a propellant charge and to a method of manufacturing it. For a long time, specialists have been concerned with the design of propellant charges and methods of manufacturing them. An increase in the interior ballistic performance so as to obtain a higher muzzle velocity for a given projectile is one goal of this research.
A known propellant charge and method of manufacture thereof is disclosed in unexamined German patent application No. OS 32 05 152. That application concerns a propellant charge for cartridge ammunition and a method for the manufacture thereof by which the performance is said to be increased as compared with the prior known propellant charges, but without the simultaneous increase in expenditure of work or danger to life as a result of solvent vapors. The propellant charge powder bodies are compressed in the cartridge case to a charge density of between 1.0 and 1.5 g/cm.sup.3 by the application of external pressure, without the addition of binders and/or solvents, and they are deformed elastically to plastically by an approximately uniform or gradually varying compression, individual quantities being compressed with the same or different pressures in individual sections uniformly or with gradual difference in the cartridge case. These measures are all directed at increasing the mass which is to be placed in a given cartridge case by compressing all or part of the propellant charge.
As a result of the elimination of binders and/or solvents, the danger in manufacture is reduced. However, the methods indicated above do have several disadvantages. After compacting, measures must be taken by means of a special covering to stabilize a free pressing rim or the charge surface of the compressed propellant charge powder body against crumbling and/or ejection of the pressing surface. Since several compacting steps are necessary, the cartridge case in question must, for reasons of safety, be brought into a separate room for the compacting after each introduction of loose propellant charge powder.
In order to fully understand the background of the present invention, several distinctions must be made regarding gas pressure in gun barrels. First, there is what is called the "design gas pressure" which is a theoretical maximum gas pressure a gun barrel will tolerate without causing a permanent change in shape of the gun barrel. Next, there is what is called the "acceptance gas pressure" which is the pressure to which a new gun barrel is subjected one or more times in order to check its safety. The acceptance gas pressure is close to the design gas pressure and generally slightly less than it. Next, there is the "maximum permissible gas pressure", which, except upon the acceptance check, must not be exceeded even under unfavorable conditions. There is also the "average gas pressure" at 50.degree. C. powder temperature, which is below the maximum permissible gas pressure. Finally, there is the "average maximum gas pressure" at 21.degree. C. powder temperature, which is used under Central European conditions as a reference value for the life of gun barrels.
By way of further explanation, two diagrams are attached FIGS. 1a and 1b). These figures show, in a case of loosely poured powder charge, the influence of use temperature on muzzle velocity and on average maximum gas pressure. The basis for these figures is a propellant powder charge which has no abnormality in pressure in the lower use temperature range, for example in the form of pressure peaks.
One essential fact which can be noted from the diagrams is that the gas pressure increases with the temperature of use, hand in hand with which there is an increase in the muzzle velocity, by its sharp rise towards the maximum permissible gas pressure. The p,T curve shows that there is a sensitive limit established by said gas pressure.